1. Field of the Invention
This invention relates to tape dispensers and applicators and more particularly to dispensers and applicators for paper tape used to seal dry-wall joints.
2. Description of the Prior Art
Interior walls of buildings are commonly finished with sheets of wall board, commonly known as sheet rock, plaster board or gypsum board. Side edges of such sheets are beveled on the outer surface so that an elongate concave region is formed along edges of abutting sheets. Joints in the concave region are first covered with a layer of mastic compound. A strip of special dry-wall joint tape is applied to and embedded in the compound while it is still soft and a finishing coat of compound is applied thereover and trowelled smoothly to form a hidden joint. The dry-wall tape reinforces the compound and is meant to prevent cracking thereof.
Hand finishing of joints in this manner is time consuming and it is desirable that at least portions of the operation be mechanized. The portion which best lends itself to mechanization is application of the dry-wall tape, since the tape need only be applied to an existing layer of mastic compound and pressed thereinto so that it adheres to it. It is a more difficult operation to smoothly and evenly apply layers of compound.
However, mechanical application of the tape presents problems not readily overcome. The dry-wall tape is non-adhesive and relies upon the stickiness of the mastic compound for adherence, therefore, the tape must be applied to the compound before the compound cures, while it is still soft. This dictates that the applied tape not be required to supply the force necessary to withdraw the tape from the tape supply, otherwise applied portions of the tape may be dragged along the compound or pulled loose from it. Also the tape, being comprised of many layers of paper, is tough and difficult to cut, requiring substantial cutting pressure.
Although there is available one known machine (the Ames Automatic) for applying dry-wall tape in open area, such machine is impractical for relatively small jobs, and because it is large and requires two hands to operate, cannot be used in areas where an operator has only one hand free or in restricted areas where there is insufficient room to manipulate a two handed machine. Such restricted spaces are common and may, for example, be found in small closet areas or around heating and cooling ducts.
A relatively small machine capable of one handed operation is required for such restricted spaces, and such machine must be capable of applying tape along a section of joint, cutting the tape off at the end of that section and advancing a new end of tape for applying to a next section of joint. This must all be done with one hand and must be done faster than manual application of the tape can be accomplished. Also, such machine must be light in weight and capable of operation without undue fatigue of the operator's hand. It should also be capable of either left or right handed operation. Furthermore, the machine should be relatively inexpensive, but be capable of withstanding constant use with the attendant abuses.
Heretofore, to the applicant's knowledge, no such machine having these characteristics as just described has been available for applying dry-wall tape.